I've started racking my planks, and they are 3/4 inch pre-finished maple. I'm wondering what nifty tricks there might be for putting these down under the cabinet fronts.

I'm running the plans length-wise along the cabinets, with the tongue towards the cabinets. The cabinet fronts sit forward about 5 inches, and about 4 inches up. So obviously I can't staple through the tongue.

I'm guessing my only option is to glue and top-nail planks that run under cabinet fronts like this. Are there any other options for putting down planks that run under cabinet fronts this way?

If the answer is to top nail and fill the holes, is it easy to find good filler that will match?

When running flooring under the cabinet toe kicks, gluing the flooring down is the only viable option. I often use PL Premium Urethane adhesive in a caulking tube. You need to clean off any excess on the surface right away. This stuff sticks incredibly. I'll use shorter boards as they're easier to install under those kicks. No need to face nail. You can put wedges between the boards and the cabinet to ensure they stay in place while the glue dries.